Anderson-Type Heteropolymolybdates Containing Tris(alkoxo) Ligands: Synthesis and Structural Characterization

Anderson-type molybdopolyanions containing tris(alkoxo) ligands [MMo6O18{(OCH2)3CR}2]3− (M = MnIII, FeIII) and [H2MMo6O18{(OCH2)3CR}2]2− (M = NiII, ZnII), (R = CH3, NO2, CH2OH), were prepared by treatment of [N(C4H9)4]4[α-Mo8O26] with tris(hydroxymethyl)methane derivatives in the presence of manganese(III) acetylacetonate, iron(III) acetylacetonate, nickel(II) acetate, or zinc(II) acetate. The complexes were structurally characterized in solution, and also by single-crystal X-ray diffraction in the cases of [N(C4H9)4]3[MnMo6O18{(OCH2)3CNO2}2], [N(C4H9)4]2[H2NiMo6O18{(OCH2)3CCH2OH}2], and [N(C4H9)4]2[H2ZnMo6O18{(OCH2)3CCH3}2]. Two tris(alkoxo) ligands replace the six hydroxo groups usually found in Anderson polyanions of formula [H6MMo6O24]n−. The complex structures may be divided into two groups: In the first one the tris(alkoxo) ligands are bound entirely to the central heteroatom, while in the second one they cap a tetrahedral cavity. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)